What is the cause of diesel common rail P1011 fault?
2 Answers
P1011 and P1012 indicate that the low-pressure fuel circuit cannot supply sufficient fuel to the fuel pump. Under heavy load conditions, the engine requires a larger fuel supply. When the fuel supply is insufficient, the ECU will limit the engine's operation, and in severe cases, it may cause the engine to stall. It is necessary to inspect the low-pressure fuel circuit system. Generally, for BOSCH systems, the fuel filter must be replaced every 10,000 kilometers. The working principle of diesel engine ignition is as follows: 1. Intake stroke: The working medium entering the cylinder is pure air. Due to the lower resistance in the diesel engine's intake system, the intake end pressure pa=(0.85～0.95)p0 is higher than that of gasoline engines. The intake end temperature Ta=300～340K is lower than that of gasoline engines. 2. Compression stroke: Since the compressed working medium is pure air, the compression ratio of diesel engines is higher than that of gasoline engines (generally ε=16～22). The compression end pressure is 3000～5000 kPa, and the compression end temperature is 750～1000K, significantly exceeding the auto-ignition temperature of diesel (approximately 520K).
P1011 fault is common in diesel common rail vehicles, mainly due to insufficient boost pressure. Last time I encountered this code, the car felt sluggish. After inspection, it turned out to be a vacuum line leak – once the air escaped, the turbo had trouble boosting. Common causes include aged/cracked hoses, faulty MAP sensors, or turbocharger carbon buildup/sticking. Dust blockage in the intake system can also trigger this fault code. I always remind friends to change air filters regularly to prevent dust issues. First confirm the specific problem with an OBD scanner, then systematically check for loose wiring connections. Ignoring it may lead to engine overheating or power reduction, costing more to repair later. Those with mechanical skills can inspect pipes for leaks themselves, but be careful not to disturb other components – better to find a reliable repair shop. Regular maintenance checks on hose conditions can save much trouble.
